Communication Management Device and Communication System

This application is a continuation application of International Application Number PCT/JP2023/025817 filed on July 13, 2023 and designated the U.S., the entire contents of which are incorporated herein by reference.

The present disclosure relates to a communication management device, a base station device, a communication system, and a communication management method for radio communication.

3 3 rd In a standardization organization such asGeneration Partnership Project (GPP) (registered trademark) or Open RAN (O-RAN) Alliance, there is a discussion about network energy saving (NES) of a radio access network (RAN). For example, in an O-RAN architecture in which a RAN intelligent controller (RIC) is introduced based on a 3GPP specification, it is expected to realize efficient network energy saving by collecting configuration information and statistical information regarding a RAN and user equipment (UE) via a standard interface and executing control according to a situation of the RAN.

As one of use cases for network energy saving of a radio access network, carrier and cell switch off/on control has been proposed. In the carrier/cell switch Off/On control, in a network configuration in which a plurality of cells (or carriers) cover the same service area, some cells (or carriers) can be stopped according to a communication status. Accordingly, network energy saving is realized. The function deployment of the carrier/cell switch Off/On control in the O-RAN architecture is discussed in WG1 (Working Group 1) and WG2 (Working Group 2) of the O-RAN (for example, Non-Patent Literatures 1 and 2).

Non-Patent Literature 1: O-RAN.WG1.Use-Cases-Detailed-Specification-R003-v10.00.03

Non-Patent Literature 2: O-RAN.WG2.Use-Case-Requirements-R003-v07.00

Non-Patent Literature 3: 3GPP TS32.423 V17.6.0

Non-Patent Literature 4: 3GPP TS32.422 V17.10.0

As described above, cell/carrier switch off/on control has been proposed as one of use cases for network energy saving of a radio access network. However, the proposed method may not be able to control network energy saving of the radio access network and load distribution of traffic with good balance.

A communication management device according to one aspect of the present disclosure manages communication of a radio access network including a first base station that provides a first cell and a second base station that provides a second cell including the first cell. The communication management device includes a network energy saving processor that executes network energy saving control of the radio access network. When traffic volumes of the first and second cells become less than a predetermined threshold, the network energy saving processor connects a terminal connected to the first base station to the second base station and shifts an operation mode of the first base station from a normal mode to a network energy saving mode, transmits, to the second base station, an instruction indicating acquisition of location information of each terminal connected to the second base station and receives the location information from the second base station, and determines whether to return the operation mode of the first base station from the network energy saving mode to the normal mode based on the traffic volume of the second cell and the location information.

The object and advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the disclosure.

1 FIG. 1 2 1 2 1 2 illustrates an example of cell/carrier switch off/on control. In this implementation example, a base station BSprovides a cell A and a base station BSprovides a cell B. A cell represents a communicable area provided by a base station. The cell B is larger than the cell A. The cell A is included in the cell B. That is, a terminal located in the cell A can communicate with both the base stations BSand BS. The base stations BSand BSare, for example, a next generation NodeB (gNB) or a new radio (NR) base station.

1 2 1 1 1 2 2 2 Terminals UEand UEare located in the cell B. The terminal UEis further located in the cell A. Accordingly, the terminal UEis connected to the base station BS. On the other hand, the terminal UEis located outside of the cell A. Accordingly, the terminal UEis connected to the base station BS. Here, a communication management device (not illustrated) manages communication between the cells A and B. The communication management device has a function of saving power of the network.

2 1 2 1 1 1 2 The communication management device monitors traffic of each cell. For example, when the base station BScan process the traffic of the terminals UEand UE, the communication management device disconnects a link between the terminal UEand base station BS, and sets up a link between the terminal UEand the base station BS. At this time, the communication management device executes the following preprocessing.

(1) checking an emergency call and a warning message in the cell A

1 (2) executing handover of the terminal UEfrom the cell A to the cell B.

(3) releasing carrier aggregation or dual connectivity when carrier aggregation or dual connectivity including the cell A is in progress.

1 1 1 Thereafter, the communication management device controls the cell A to be turned off. For example, the communication management device stops output of the base station BS. When the base station BSuses a plurality of carriers, the base station BScan stop some carriers.

1 2 In this way, according to the cell/carrier switch off/on control, when traffic of a radio access network is small, the cell A can be stopped while maintaining the communication between the terminal UEand the terminal UE. Accordingly, network energy saving of the radio access network is realized.

As described above, in the cell/carrier switch off/on control, the communication management device monitors the traffic of each cell. In addition, the communication management device monitors a radio wave condition and the like of each cell. However, in the proposed cell/carrier switch off/on control, location information of each terminal UE is not used. Therefore, in the proposed method, efficiency of network energy saving may deteriorate.

2 FIG. 1 FIG. 1 2 2 illustrates an example of a problem caused due to non-use of the location information of the terminal UE. In this example, as described with reference to, the cell A is controlled to an OFF state. The terminals UEand UEare connected to the base station BS.

3 6 1 2 Thereafter, it is assumed that traffic in the cell B increases. Specifically, the terminals UEto UElocated in the cell B start communication. It is assumed that a communication management device determines that communication performance may degrade due to an increase in traffic in the cell B. In this case, the communication management device executes an offload process (alternatively, load balance processing) of distributing the traffic in the cell B to the base stations BSand BSby returning the cell A to an ON state.

2 FIG.(A) 1 6 1 3 4 1 3 4 1 1 2 In the case illustrated in, of the terminals UEto UElocated in the cell B, the terminals UE, UE, and UEare located in the cell A. In this case, when the cell A is controlled to the ON state, the terminals UE, UE, and UEcan be connected to the base station BS. Then, since traffic in the cell B is distributed to the base stations BSand BS, communication performance can be maintained.

2 FIG.(B) 1 6 1 2 6 2 On the other hand, in the case illustrated in, of the terminals UEto UElocated in the cell B, only the terminal UEis located in the cell A. In this case, even if the cell A is controlled to the ON state, the terminals UEto UEcontinue communication with the base station BS. That is, even if the cell A is controlled to the ON state, the load distribution effect in the cell B is low. In other words, although the load distribution effect is low, power consumption increases in the control of the cell A to the ON state. Accordingly, in this case, the efficiency of the power saving effect is poor.

A communication management device according to an embodiment of the present disclosure collects location information of each terminal UE in cell/carrier switch off/on control. The communication management device executes the cell/carrier switch off/on control not only based on traffic in the cell but also based on location information of each terminal UE.

3 FIG. 3 FIG. 10 2 22 23 illustrates an example of function deployment related to cell/carrier switch off/on control in an O-RAN architecture. In the example illustrated in, a communication system related to the cell/carrier switch off/on control includes a service management orchestration (SMO), an Enode, and an O-RAN radio unit (O-RU).

10 10 2 22 23 1 10 23 10 1 10 2 22 1 10 23 The SMOis an example of a communication management device and manages each device or each function in the O-RAN architecture. The SMOis connected to the Enodeand the O-RUvia an Ointerface. The SMOis connected to the O-RUvia an open fronthaul interface. The SMOmay collect configuration information and statistical information of the radio access network via the Ointerface or the open fronthaul interface. The SMOcan transmit an instruction to change the configuration of the Enodevia the Ointerface. Further, the SMOcan control an operation of the O-RUvia the open fronthaul interface.

11 21 11 10 21 10 11 21 1 1 1 1 The O-RAN architecture includes a RAN intelligent controller (RIC). The RIC provides services for each device or each function in the O-RAN architecture. However, the RIC includes a non-real time RICand a real time (near-real) time RIC. The non-real time RICis mounted inside the SMOand the real time RICis provided outside of the SMO. The non-real time RICand the real time RICare connected by an Ainterface. The Ainterface includes A-P and A-EI.

11 11 The non-real time RICincludes a non-real time RIC framework. A control application related to the cell/carrier switch off/on control operates on the non-real time RIC framework. In this example, a network energy saving (NES) application and a coverage and capacity optimization (CCO) application are mounted. The application program operating in the non-real time RICmay be referred to as “rApp”.

10 2 The NES application acquires configuration information and statistical information of a radio access network collected by the SMO, and gives the information to an artificial intelligence (AI)/machine learning (ML) model to execute a learning process. The NES application updates the AI/ML model. Further, the NES application estimates optimum configuration information of the Enode by using the AI/ML model. The CCO application manages coverage information of each cell.

11 2 22 1 11 2 1 11 21 1 21 1 21 1 In this way, the non-real time RICcollects various types of data accumulated in the Enodevia the Ointerface. The non-real time RICdetermines an optimum setting parameter according to the wireless environment and a traffic volume, and gives the setting parameter to the Enode via the Ointerface by using AI/ML. Further, the non-real time RICgenerates a policy related to control of the radio access network and notifies the real time RICof the policy via the Ainterface. For example, the real time RICis notified of a policy “Executing network energy saving to 50% of peak power” via the A-P interface. Alternatively, the real time RICis notified of information indicating geographical overlap of a coverage of each cell via the A-EI interface.

21 2 22 2 21 2 11 21 11 21 The real time RICcollects configuration information and statistical information of a radio access network from the Enodevia the Einterface and analyzes the configuration information and the statistical information. The real time RICcontrols the Enode according to the policy of which the non-real time RICnotifies. The preprocessing (1) to (3) described above may be started by the real time RICin response to an instruction from the non-real time RIC. The application program operating in the real time RICmay be referred to as “xApp”.

2 22 2 22 23 23 21 2 22 2 22 The Enodeincludes an O-RAN central unit (O-CU) and an O-RAN distributed unit (O-DU). The Enodeprovides radio link control, media access control, a PHY-High function, and the like and processes signals of the O-RUin an upper layer. A plurality of O-RUscan be connected to the O-DU. The configuration information and the statistical information of the radio access network are obtained and provided to the real time RIC. The preprocessing (1) to (3) described above is executed by the Enode. The Enodecan be described as, for example, a communication control device.

23 23 10 1 23 10 1 23 The O-RUincludes a radio circuit and can accommodate a plurality of terminals UE. The O-RUtransmits a report related to network energy saving of the radio access network to the SMOvia an M plane of the Ointerface or the open fronthaul interface. Further, the O-RUexecutes on/off control of the cell or carrier according to the NES instruction received from the SMOvia the M plane of the Ointerface or the open fronthaul interface. Note that the O-RUcan be described as, for example, a communication device.

1 10 21 2 22 1 11 21 2 21 2 22 1 The Ointerface provides an operation administration maintenance (OAM) function from the SMOto the real time RICand the Enode. The Ainterface connects the non-real time RICto the real time RIC. The Einterface connects the real time RICto the Enode. The Rinterface connects the non-real time RIC framework to the rApp.

10 10 In the O-RAN architecture that has the above configuration, the SMOoperating as the communication management device executes network energy saving (that is, the NES) of the network while monitoring the traffic of each cell. At this time, the SMOexecutes network power saving not only based on traffic of each cell but also based on location information of each terminal UE.

4 FIG. 4 FIG. 3 FIG. 1 2 1 2 2 22 1 2 illustrates an example of a flow of information in the network energy saving control according to the embodiment of the present disclosure. In, the O-CUand the O-CUare included in an O-CU. The O-CU may be realized by one information processing device or may be realized by a plurality of physically independent information processing devices. Similarly, the O-DUand the O-DUare included in an O-DU. The O-DU may be realized by one information processing device or may be realized by a plurality of physically independent information processing devices. The O-CU and the O-DU correspond to the Enodeillustrated in. The O-RUand the O-RUmay each accommodate the terminal UE.

1 1 1 2 2 2 2 1 FIG. 1 FIG. The O-CU, the O-DU, and the O-RUare included in a base station BS1 that provides the cell A illustrated in. The O-CU, the O-DU, and the O-RUare included in a base station BSthat provides the cell B illustrated in.

10 11 12 12 3 FIG. The SMO(alternatively, the non-real time RIC) includes a network energy saving processing unit. The network energy saving processing unitis realized by the NES application and the CCO application illustrated in.

10 1 10 12 1 10 10 1 10 1 2 1 The SMOcollects the configuration information and the statistical information of the radio access network from the O-CU through the Ointerface constantly or periodically. For example, the SMOcollects information indicating a radio wave status of each terminal UE (reference signal received power (RSRP), reference signal received quality (RSRQ), and the like), information indicating a traffic volume of each terminal UE, information indicating a throughput of each terminal UE, and the like. Then, the network energy saving processing unitdetermines whether to shift an operation mode of the base station BSfrom the normal mode to the network energy saving mode based on the information collected by the SMO. In the normal mode, the base station can communicate with each terminal UE located in the cell. In the network power saving mode, in this implementation example, the base station stops some or all of the available carriers. That is, the cell or the carrier is controlled to the OFF state. This operation is realized by the O-RU. That is, the SMOcontrols the operation mode of the base station by providing an instruction or a command to the O-RU via the Ointerface. For example, when a total traffic volume of the cell A and the cell B becomes less than a predetermined threshold, the SMOconnects the terminal UE connected to the base station BSto the base station BSand shifts the operation mode of the base station BSfrom the normal mode to the power saving mode.

1 12 2 2 1 After the base station BSis shifted to the network energy saving mode, the network energy saving processing unitnotifies the O-CU (that is, the O-CU) of the base station BSof the setting related to the UE measurement information such that each terminal UE located in the cell B executes minimization of drive test (MDT)/trace record notification. This notification is transmitted via the Ointerface.

2 2 2 12 The O-CUnotifies each terminal UE located in the cell B of an MDT/Trace record to be reported. This notification is realized by, for example, an RRC connection reconfiguration message. Then, each terminal UE transmits an MDT/Trace record to the O-CUaccording to the notification from the O-CU. The MDT/Trace record includes UE measurement information and UE location information specified by the network energy saving processing unit.

2 1 2 The MDT/Trace record is set, for example, in accordance with chapter 4.34.1 (Trace Record for Immediate MDT measurements) and chapter 4.34.2 (Trace Record for UE location information) of Non-Patent Literature 3. Specifically, RSRP information and RSRQ information are reported as UE measurement information from each terminal UE to the O-CUby the MMDT measurement. By UE location MDT measurement, Global Navigation Satellite System (GNSS) pos information is reported from each terminal UE to the O-CUas UE location information.

10 2 1 10 12 The MDT/Trace records transmitted from each terminal UE are communicated to the SMOvia O-CUand Ointerfaces. Then, the MDT/Trace record is collected by a trace collection entity (TCE) in the SMO. Subsequently, the MDT/Trace record is analyzed in the analysis unit and processed in a predetermined format as necessary. Thereafter, the MDT/Trace record is transmitted to the network energy saving processing unitvia the non-real time RIC framework.

1 12 10 12 12 As described above, when the base station BSis controlled to the network energy saving mode (that is, when the cell A is controlled to the OFF state), the network energy saving processing unitacquires location information of each terminal UE located in the cell B. Here, each terminal UE periodically notifies the SMOof location information indicating its own location by using the MDT/Trace record. Accordingly, the network energy saving processing unitcan accurately estimate a position and a movement trajectory of each terminal UE located in the cell B. Then, the network energy saving processing unitdetermines whether to return the cell A from the network energy saving mode to the normal mode using the position and movement trajectory of each terminal UE located in the cell B.

5 6 FIGS.to 1 FIG. 1 FIG. 1 FIG. are flowcharts illustrating an example of network energy saving control according to the embodiment of the present disclosure. Here, it is assumed that a plurality of cells are formed in the same area. For example, in the example illustrated in, two cells (cell A and cell B) are formed. The cell A is included in the cell B. That is, the cell B covers the entire cell A. In the following description, a cell (the cell A in) included by another cell may be referred to as a “narrow area cell”. Another cell (the cell B in) including a narrow area cell may be referred to as a “wide area cell”. At the start of this flowchart, it is assumed that both the narrow area cell and the wide area cell are in the ON state.

1 10 10 1 10 In S, the SMOstarts collecting the configuration information and the statistical information of the radio access network. For example, the SMOcollects, from the O-CU via the Ointerface, information (such as RSRP and RSRQ) indicating a radio wave status of each terminal UE, information indicating a traffic volume of each terminal UE, information indicating a throughput of each terminal UE, and the like. Thereafter, the SMOcollects the configuration information and the statistical information continuously or periodically.

2 12 10 12 10 3 In S, the network energy saving processing unitcompares a total traffic volume of the narrow area cell and the wide area cell with a predetermined threshold using the configuration information and the statistical information collected by the SMO. This threshold represents, for example, a traffic volume that can be sufficiently processed only by the base station of the wide area cell. Then, when the total traffic volume is less than the threshold, the network energy saving processing unitdetermines that the narrow area cell can be stopped. In this case, the process of the SMOproceeds to S.

3 10 In S, the SMOstarts preprocessing to stop the narrow area cell. The preprocessing includes the following processes:

(1) Checking an emergency call and a warning message in the narrow area cell;

(2) Executing handover from the narrow area cell to the wide area cell on each terminal UE connected to the narrow area cell; and

(3) Releasing carrier aggregation or dual connectivity when the carrier aggregation or the dual connectivity including the narrow area cell is in progress.

21 10 2 22 The preprocessing for stopping the narrow area cell is started by the real time RICin response to an instruction from the SMOand is executed by, for example, the Enode(for example, the O-CU).

4 10 10 2 10 5 In S, the SMOdetermines whether there is a terminal UE connected to the narrow area cell. When there is the terminal UE connected to the narrow area cell, the process of the SMOreturns to Safter a predetermined time (for example, several seconds) has elapsed. Thereafter, when the traffic volume is less than the above-described threshold and there is no terminal UE connected to the narrow area cell, the process of the SMOproceeds to S.

5 12 10 1 10 2 1 2 In S, the network energy saving processing unittransmits a cell stop instruction to the O-RU in the base station of the narrow area cell. The cell stop instruction is transmitted from the SMOto the corresponding O-RU via the Ointerface. Alternatively, the cell stop instruction may be transmitted from the SMOto the corresponding Enode via the Ointerface and is further transmitted from the Enode to the O-RU via the fronthaul interface. The O-RU sets the narrow area cell to the OFF state in response to the cell stop instruction. At this time, the O-RU may stop the radio circuit. Accordingly, the operation mode of the base station of the narrow area cell shifts from the normal mode to the power saving mode.

6 12 10 1 In S, the network energy saving processing unittransmits an instruction related to notification of the UE measurement information and the UE location information to the O-CU in the base station of the wide area cell. The instruction represents that each terminal UE located in the wide area cell implements notification of an MDT/Trace record. That is, the instruction includes information for causing each terminal UE located in the wide area cell to report UE measurement information (RSRP, RSRQ, or the like) and UE location information (for example, GNSS information). This instruction is transmitted from the SMOto the O-CU in the base station of the wide area cell via the Ointerface.

7 10 In S, the O-CU in the base station of the wide area cell executes activation of the MDT/Trace record for each terminal UE located in the wide area cell in response to the instruction received from the SMO. At this time, the RRC connection reconfiguration message is transmitted from the O-CU to each terminal UE. The RRC message includes information indicating an MDT/Trace record to be reported by each terminal UE. The activation of the MDT/Trace record is executed on the terminal UE that allows the management based MDT in the user consent in the UE context held by the O-CU in this implementation example. That is, the MDT/Trace record is activated on only the terminal UE permitted to provide the location information. The activation of the MDT/Trace record is described in, for example, Chapter 4.1.1.9.3 of Non-Patent Literature 4.

Each terminal UE periodically transmits a designated MDT/Trace record subsequently when the above-described activation is executed. The MDT/Trace record includes UE measurement information (RSRP, RSRQ, or the like) and the UE location information (for example, GNSS information) of the terminal UE.

8 10 1 10 12 12 4 FIG. In S, the MDT/Trace record transmitted from each terminal UE is transmitted to the SMOvia the O-CU and the Ointerface in the base station of the wide area cell. In the SMO, the MDT/Trace record is transmitted to the network energy saving processing unitvia the TCE illustrated in. As described above, when the narrow area cell is controlled to the OFF state, the network energy saving processing unitcontinuously acquires the location information of each terminal UE located in the wide area cell via the base station of the wide area cell.

11 12 10 12 In S, the network energy saving processing unitcompares the traffic volume in the wide area cell with a predetermined threshold. This threshold represents, for example, a traffic volume in which communication performance may be degraded by only the base station of the wide area cell. Then, when the traffic volume in the wide area cell exceeds the threshold, the process of the SMOproceeds to S.

12 12 12 13 15 In S, the network energy saving processing unitdetermines whether a condition for reactivating the narrow area cell in the OFF state is satisfied. This condition is expressed by, for example, the number of terminals UE located in the narrow area cell. In this case, when the number of terminals UE located in the narrow area cell is greater than a predetermined number, it is determined that the narrow area cell may be reactivated. Alternatively, the condition for reactivating the narrow area cell is expressed by the total traffic volume of the terminal UE located in the narrow area cell. In this case, when the total traffic volume of the terminal UE located in the narrow area cell is greater than the predetermined volume, it is determined that the narrow area cell may be reactivated. In any case, the network energy saving processing unitdetermines whether to reactivate the narrow area cell using the location information of each terminal UE located in the wide area cell. Then, when the narrow area cell is reactivated, the processes of Sto Sare executed.

13 12 10 1 10 2 1 2 In S, the network energy saving processing unitinstructs the O-RU in the base station of the narrow area cell to return the operation mode from the network energy saving mode to the normal mode. Accordingly, the narrow area cell is reactivated. That is, the narrow area cell is controlled to the ON state. This instruction is transmitted from the SMOto the O-RU in the base station of the narrow area cell via the Ointerface. Alternatively, the instruction may be transmitted from the SMOto the corresponding Enode via the Ointerface and further transmitted from the Enode to the O-RU via the fronthaul interface.

14 12 10 1 In S, the network energy saving processing unitreleases the MDT/Trace record setting mounted in the O-CU in the base station of the wide area cell. This release instruction is transmitted from the SMOto the O-CU in the base station of the wide area cell via the Ointerface.

15 10 In S, the O-CU in the base station of the wide area cell executes deactivation of the MDT/Trace record for each terminal UE located in the wide area cell in response to the release instruction received from the SMO. The deactivation of the MDT/Trace record is described in, for example, Chapter 4.1.3.11 of Non-Patent Literature 4.

7 8 FIGS.and 1 FIG. 2 FIG. 1 2 1 2 illustrate an implementation example of network energy saving processing according to the embodiment of the present disclosure. In this implementation example, similarly toand, the base station BSprovides the cell A, and the base station BSprovides the cell B. The cell A is included in the cell B. That is, the terminal UE located in the cell A can communicate with both the base stations BSand BS.

1 2 1 1 2 2 1 2 2 2 5 1 FIG. 7 8 FIGS.(A) or(A) 5 FIG. Terminals UEand UEare located in the cell B. The terminal UEis also located in the cell A. However, the total traffic volume of terminals UEand UEis sufficiently small relative to a capacity of base station BS. Therefore, as described with reference to, the cell A is controlled to the OFF state. As a result, as illustrated in, both the terminals UEand UEare connected to the base station BS. This procedure corresponds to Sto Sillustrated in.

6 8 10 2 2 2 10 1 12 5 FIG. When the cell A is controlled to the OFF state (that is, when the operation mode of the base station BS1 shifts from the normal mode to the power saving mode), a procedure of Sto Sillustrated inis executed. The SMOsets an MDT/Trace record to be reported by each terminal UE in the O-CU of the base station BS. The MDT/Trace record that each terminal UE is scheduled to report includes location information (for example, GNSS information) indicating a location of each terminal UE. The O-CU of the base station BSexecutes activation of the MDT/Trace record on each terminal UE located in the cell B. Accordingly, each terminal UE periodically transmits the UE measurement information and the UE location information to the O-CU of the base station BS. The information is transmitted to the SMOvia the Ointerface. Accordingly, the network energy saving processing unitcan accurately detect or estimate the position of each terminal UE.

7 FIG.(B) 8 FIG.(B) 3 6 2 1 2 3 6 2 12 1 6 Thereafter, as illustrated inor, the terminals UEto UElocated in the cell B start communication. Here, when the cell A is controlled to the OFF state, the base station BSactivates the MDT/Trace record on each terminal UE located in the cell B. Then, not only the terminals UEand UEbut also the terminals UEto UEreport the MDT/Trace record to the base station BS. Accordingly, the network energy saving processing unitcan detect or estimate the positions of the terminals UEto UE.

3 6 11 12 12 1 6 6 FIG. 6 FIG. It is assumed that the traffic in the cell B increases as the terminals UEto UElocated in the cell B start communication, and the traffic volume exceeds the threshold in Sillustrated in. Then, the network energy saving processing unitexecutes the determination of Sillustrated inusing the location information of the terminals UEto UE.

7 FIG. 6 FIG. 7 FIG.(B) 1 6 1 12 2 12 12 12 1 6 2 In the case illustrated in, of the terminals UEto UElocated in the cell B, only the terminal UEis located in the cell A. That is, the number of terminals UE located in the narrow area cell in the OFF state is one. Here, it is assumed that the threshold used in the determination of Sillustrated inis. In this case, since the number of terminals UE located in the narrow area cell in the OFF state is less than the threshold, the network energy saving processing unitdetermines that the condition for reactivating the narrow area cell is not satisfied. At this time, the network energy saving processing unitestimates that the offload effect of the cell B is small even if the cell A is returned to the ON state. Therefore, as illustrated in, the network energy saving processing unitmaintains the cell A in the OFF state (network energy saving mode). That is, the terminals UEto UEcontinue the communication with the base station BS.

8 FIG. 8 FIG.(C) 1 6 l 1 3 4 12 12 12 1 3 4 1 2 In the case illustrated in, of terminals UEto UEocated in the cell B, the terminals UE, UE, and UEare located in the cell A. That is, the number of terminals UE located in the narrow area cell in the OFF state is three. In this case, since the number of terminals UE located in the narrow area cell in the OFF state is greater than the threshold, the network energy saving processing unitdetermines that the condition for reactivating the narrow area cell is satisfied. At this time, the network energy saving processing unitestimates that the offload effect of the cell B is large when the cell A is returned to the ON state. Accordingly, as illustrated in, the network energy saving processing unitreturns the cell A to the ON state (normal mode). As a result, traffic of the terminals UE, UE, and UEis processed by the base station BS, and thus performance of the base station BSdoes not degrade.

8 FIG. 6 FIG. 14 15 12 2 2 In the case illustrated in, thereafter, a procedure of Sand Sillustrated inis executed. That is, the network energy saving processing unitreleases the setting of the MDT/Trace record set in the base station BS. The base station BSdeactivates the MDT/Trace record on each terminal UE located in the cell B.

10 7 FIG. 8 FIG. As described above, according to the embodiment of the present disclosure, when the narrow area cell is controlled to the OFF state, the SMOoperating as a communication management device can accurately detect or estimate a position of each terminal UE located in the wide area cell including the narrow area cell. Accordingly, it can be appropriately determined whether to return the narrow area cell to the on-state in consideration of the offload effect when the traffic volume increases. For example, in the case illustrated in, even when the cell A is returned to the ON state, the offload effect of the cell B is estimated to be small, and thus the cell A is maintained in the OFF state. Accordingly, wasteful power consumption in the cell A is reduced. Conversely, in the case illustrated in, when the cell A is returned to the ON state, the offload effect of the cell B is estimated to be large, and thus the cell A is controlled from the OFF state to the ON state. Accordingly, communication performance of the cells A and B is maintained.

9 FIG. 12 is a sequence diagram illustrating an example of a method in which the network energy saving processing unitcollects the location information of the terminal UE. Note that it is assumed that the narrow area cell is controlled to the OFF state before this sequence is started.

12 1 2 22 1 2 22 12 The network energy saving processing unit (NES)generates an instruction related to the setting of the MDT/Trace record and transmits the instruction to the non-real time RIC framework via the Rinterface. The non-real time RIC framework transmits an instruction related to the configuration of the MDT/Trace record to the base station of the wide area cell. Specifically, an instruction related to the configuration of the MDT/Trace record is transmitted to the Enodevia the Ointerface. Here, the Enodeincludes an O-CU and an O-DU. Then, the O-CU transmits the RRC connection reconfiguration message to each terminal UE in response to the instruction from the network energy saving processing unit. Accordingly, activation of the MDT/Trace record of each terminal UE is executed. At this time, as the information to be reported by the terminal UE, location information indicating the position of the terminal UE is designated in addition to the information indicating the radio wave conditions (RSRP, RSRQ, or the like).

1 12 12 The terminal UE transmits the MDT/Trace record to the base station of the wide area cell. That is, the MDT/Trace record of the terminal UE is transmitted to the O-CU. The MDT/Trace record includes location information of the terminal UE in addition to the information (RSRP, RSRQ, or the like) indicating a radio wave status of the terminal UE. The O-CU transmits this MDT/Trace record to the non-real time RIC framework via the Ointerface. The non-real time RIC framework transmits the MDT/Trace record to the network energy saving processing unit. At this time, the non-real time RIC framework may optionally analyze and process the MDT/Trace record. In this way, the network energy saving processing unitcan collect the location information of each terminal UE.

10 FIG. 10 100 101 102 103 104 105 106 illustrates an example of a hardware configuration of the SMOthat operates as a communication management device. The communication management device is realized by a computerincluding a processor, a memory, a storage device, an input/output device, a recording medium reading device, and a communication interface.

101 10 103 101 12 102 101 103 3 FIG. The processorcontrols the operation of the SMOby executing a communication management program stored in the storage device. Here, the communication management program includes various rApps illustrated in. That is, the communication management program includes an NES and a CCO. Accordingly, the processorprovides a function of the network energy saving processing unitby executing this communication management program. The memoryis used as a work area of the processor. The storage devicestores the above-described communication management program and other programs.

104 104 105 110 110 100 110 110 100 106 120 100 120 The input/output devicemay include an input device such as a keyboard, a mouse, a touch panel, or a microphone. The input/output devicemay include an output device such as a display device or a speaker. The recording medium reading devicemay acquire data and information recorded in the recording medium. The recording mediumis a removable recording medium detachable from the computer. The recording mediumis realized by, for example, a semiconductor memory, a medium that records a signal through an optical action, or a medium that records a signal through a magnetic action. The communication management program may be provided from the recording mediumto the computer. The communication interfaceprovides a function of connecting to a network. When the communication management program is stored in the program server, the computermay acquire the server program from the program server.

According to the foregoing aspect, efficiency of network energy saving of a radio access network is improved.

All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the disclosure and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the disclosure. Although one or more embodiments of the present disclosure have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure.